IISc's mobile robot can help in household work

It can move in a stable manner on uneven surfaces

IISc's mobile robot can help in household work

Robotic engineers at the Indian Institute of Science (IISc) have designed a wheeled mobile robot that can move in a stable manner on an uneven terrain with minimal slipping.

Prof Ashitava Ghosal from the Department of Mechanical Engineering, the Indian Institute of Science, and Dr Tharakeshwar Appala from SSJ Engineering College, Hyderabad, have successfully demonstrated a prototype of an “autonomous mobile robot” that can travel in a straight line, make turns and also switch lanes on bumpy terrain, without the risk of falling off and with minimal slip.

Autonomous mobile robots are capable of navigating in unknown and unstructured environments and have the capability of negotiating rough terrains with minimal intervention from human operators. This makes them suitable for activities such as household cleaning, delivering goods and services and planetary exploration.
NASA’s ‘Curiosity’ Mars rover, currently exploring the surface of the Red Planet, is an excellent example of an autonomous mobile robot.

Common problem
A common problem with these robots is the slip at the wheel-ground contact. “When a wheel slips, during the rotation of the wheel, the robot’s location is unchanged and this leads to localisation errors,” explains Prof Ghosal. He also notes that the wheel slip leads to power wastage – a premium resource in planetary exploration. Wheel slip can also lead to unstable motion and the robot can tip over or fall on the uneven terrain. Motivated by this challenge, the team at the IISc focused on designing robots that do not slip and are stable in such terrains.

In the proposed design, the robot consists of one front wheel and two torus-shaped rear wheels connected to a platform. The wheels are designed to always keep contact with the ground and they are driven by motors. The rear wheels are connected to the platform through a suspension mechanism having four links. Two of the links are fixed and the other two are free to move at an angle.

Enables lateral tilting
This enables lateral tilting of the wheel, thus preventing a slip. The performance of the robot was assessed for three types of desired paths: straight line, a circular motion of 30 degrees and a lane change. With the new design, the team observed 50 per cent reduced slippage in comparison with previous models.

The applications of such autonomous wheeled robots are enormous. “Rover ‘Opportunity’ sent by NASA has been successfully exploring Planet Mars for more than seven years now. In my opinion, apart from planetary missions, the wheeled robots will find increasing use in industry and security related applications in India,” points out Prof Ghosal.

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